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September Weather in Bethesda, United States

Last updated: June 24, 2025

In September, the average temperature in Bethesda, United States hovers around 20°C (68°F), with a range that sees lows of 5°C (42°F) and highs reaching up to 34°C (94°F). Expect about 114 mm (4.5 in) of precipitation over approximately 9 days, along with an average humidity level of 73%. Perfect for those who enjoy a balance of warmth and a touch of moisture in the air!

September Temperature in Bethesda

In September in Bethesda, the average temperature is 20°C (68°F), with maximums reaching 34°C (94°F) and minimums dropping as low as 5°C (42°F). This varied climate makes Bethesda a versatile destination for travelers, offering both warm sunny days and cooler evenings.

September Weather in Bethesda: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Bethesda, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Bethesda, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (94°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec323643526370757368584337
Data source: Temperature data for Bethesda generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Bethesda

In Bethesda in September, the precipitation amount is 114 mm (4.5 in) over the course of 9 days.

September Precipitation Trends in Bethesda

The chart displays monthly precipitation patterns in Bethesda, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Bethesda, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec931211191421411651339511412092114
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Bethesda

In Bethesda in September, humidity is 73%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making outdoor activities somewhat sticky, yet the atmosphere remains pleasant for leisurely strolls and sightseeing.

September Average Humidity in Bethesda

This chart illustrates the average monthly humidity levels in Bethesda, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Bethesda is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%88%87%82%84%82%73%74%81%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Bethesda

In Bethesda in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Bethesda.

Maximum UV Index Levels in Bethesda for September

The chart shows the monthly maximum UV Index (UVI) for Bethesda in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Bethesda typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098643
Data source: Bethesda September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Bethesda Compares to Other Months

Weather in Bethesda varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Bethesda, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Bethesda, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (32°F)93 mm (3.7 inches)88%moderate
February Weather2°C (36°F)121 mm (4.8 inches)88%moderate
March Weather6°C (43°F)119 mm (4.7 inches)88%high
April Weather11°C (52°F)142 mm (5.6 inches)86%very high
May Weather17°C (63°F)141 mm (5.6 inches)82%very high
June Weather21°C (71°F)165 mm (6.5 inches)84%very high
July Weather24°C (75°F)133 mm (5.2 inches)82%very high
August Weather23°C (73°F)95 mm (3.7 inches)73%very high
September Weather20°C (68°F)114 mm (4.5 inches)73%very high
October Weather14°C (58°F)120 mm (4.7 inches)81%high
November Weather6°C (43°F)92 mm (3.6 inches)89%moderate
December Weather3°C (37°F)114 mm (4.5 inches)86%moderate

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